1275-1325;Middle Englishalleg(g)en, probably < Old Frenchaleguer (< Medieval Latin,Latinallēgāre to adduce in support of a plea; see allegation), conflated with Anglo-French,Old Frenchaleg(i)er to justify, free, literally, to lighten (< Late Latinalleviāre; see alleviate); homonymous Middle English v. alleg(g)en, with literal sense of Old Frenchaleg(i)er, replaced by allay in 16th cent.

c.1300. It has the form of one French verb and the meaning of another. The form is Anglo-French aleger, Old French eslegier "to clear at law," from Latin ex- "out of" (see ex-) and litigare "bring suit" (see litigate); however eslegier meant "acquit, clear of charges in a lawsuit." It somehow acquired the meaning of French alléguer, from Latin allegare "send for, bring forth, name, produce in evidence," from ad- "to" (see ad-) + legare "to depute, send" (see legate). Related: Alleged; alleging.